Electronic devices, particularly integrated circuits and semiconductors are often coated or encapsulated with a polymeric silicone resin, such as a room temperature vulcanized (RTV) or heat cured silicone elastomers, to protect the device from mechanical damage and from adverse environmental effects of temperature and humidity.
The silicone elastomer encapsulants which are generally employed, are used in very small quantities on the device and are transparent in color so that they are not readily visible by the naked eye. This transparency, especially when employed in relatively thin coatings, makes the encapsulant difficult to see for inspection purposes with the naked eye. Since quality control techniques which are generally employed in the production of encapsulated devices often require visual inspection of the devices to insure that the encapsulant has been placed over the device and is adherent thereto, it would be highly beneficial to modify the silicone elastomer so that it became highly colored and readily visible to the naked eye. However, any additive which is employed with the elastomer should preferably be employed in very small quantities requiring it to have a high molar extinction coefficient in the visible range and should in no way adversely effect the electrical or mechanical properties of the silicone elastomer and of course should be soluble in the elastomer at least in the quantity required to impart sufficient coloration. Such a colorant has now been found.